1. Field of the Invention
The present invention relates to an ink jet recording apparatus that records by discharging ink droplets to a recording material. More particularly, the invention relates to a conveying device of a recording material, which is capable of significantly reducing the adhesion of the contact marks on the recording material that may be made by the rotational member when carrying out the expelling conveyance of the recording material by keeping contact with the recording surface of the recording material after ink jet recording, and which is also capable of attempting the stabilized conveyance of a recording material. The invention also relates to an ink jet recording apparatus that uses such device.
2. Related Background Art
The recording apparatus provided with the function of a printer, a copying machine, a facsimile, or the like, or used as the output equipment of complex electronic equipment or a work station, which includes a computer, word processor, or the like, is arranged to record on a recording material (recording medium) such as a paper sheet, a thin plastic sheet, in accordance with image information.
Of such recording apparatuses, an ink jet recording apparatus has problems given below.
For example, when recording is made on the trailing end portion of a recording material, and then, the recording material is being expelled, the conveyance thereof becomes unstable in a case where a recording material having a high rigidity is used or a large curling occurs at the time of recording or in a case where the recording material is conveyed at ultra-high speed.
Generally, in an ink jet recording apparatus, a structure is arranged to eject (expel) a recording material after recording in such a manner that an expelling conveyance roller, which is in contact with the backside of a recording material under pressure, and a rotational member (hereinafter referred to as a “spur”) that has plural extrusions on the circumference thereof as shown in FIG. 11A are arranged so that the spur is in contact with the recording surface side and made rotative following the rotation of the expelling conveyance roller, and that the recording material after recording is expelled by rotating the extrusions thereof, which are in contact under pressure on the surface having the adhesion of ink droplets.
Now, if the biasing pressure of the spur to a recording material in order to effectuate the stable conveyance thereof, the rotation load to the spur is increased by the pressure thus increased in addition to the causes brought about directly by the increased pressure in some cases. FIG. 10 shows the conventional structure, and when the amount of deformation (a warping amount) of the spur spring 37 is conditioned to be approximately 1 mm, it is in contact with the inner circumference of the spur 36 on the edge portion 37b on the inner side when the edge portion 37a on the outer side is biased. Then, the rotational load on the spur 36 becomes large.
The increased rotational load on the spur such as this impedes the normal rotation of the spur eventually, and the spur causes damage to the recording material. If the recording material is such that it has a surface coating layer, the problem encountered is such as to peel off the coating layer.
Also, as a driven-rotational member (roller) for use of a sheet expeller of the kind, there is a rotational member having curved circumferential surface (hereinafter referred to as a “rotational member with curved circumferential surface”), which is continuously in contact with a recording material by a contact area of as small as possible as shown in FIG. 11B. Even with the rotational member with curved circumferential surface, a recording material is damaged more or less as described above in a condition that the rotational member is forced to be in contact therewith under a strong pressure due to defective rotation. There is a problem encountered that transferred ink or the coating layer is peeled off.
Further, if a countermeasure is taken respectively for the rotational member with curved circumferential surface and the spur-rotational member to increase the number of rotational members instead of intensifying the biasing pressure to a recording material, there is a problem encountered that such countermeasure leads to a significant increase of costs.